Re: [PATCH] xen/blkback: add xen-blkback support

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

Talk about self-review :-)

> index 90f22cc..9b60e69 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -351,6 +351,7 @@ void blk_put_queue(struct request_queue *q)
>  {
>  	kobject_put(&q->kobj);
>  }
> +EXPORT_SYMBOL_GPL(blk_put_queue);
>  
>  /*
>   * Note: If a driver supplied the queue lock, it should not zap that lock
> @@ -572,6 +573,7 @@ int blk_get_queue(struct request_queue *q)
>  
>  	return 1;
>  }
> +EXPORT_SYMBOL_GPL(blk_get_queue);
>

.. snip..
> +static void dispatch_rw_block_io(struct blkif_st *blkif,
.. snip..
> +	struct request_queue *q;

.. snip

> +	q = bdev_get_queue(preq.bdev);
> +	if (!q)
> +		goto fail_response;
.. snip..
> +	/* Get a reference count for the disk queue and start sending I/O */
> +	blk_get_queue(q);
> +	blk_start_plug(&plug);
> +
> +	for (i = 0; i < nbio; i++)
> +		submit_bio(operation, biolist[i]);
> +
> +	blk_finish_plug(&plug);
> +	/* Let the I/Os go.. */
> +	blk_put_queue(q);

Hmm, let me remove those get/puts. They are actually not necessary as we
already hold a reference count when we opened the device.